Just bought a 2004 Ford Superduty 6.0Liter since my bearing spun in my 1999 f250 and lost oil pressure. 4 days into driving and here's my problem. Ok, I have searched forums since 5am for any advice before posting. My problem started as I was driving to work I noticed my abs light came on then the battery light. I immediately pulled over shut off the truck, tried to restart, and no go. Got a jump off , made it to work, started out for lunch and no go. Took out the alternator , had it bench tested , autozone said fail. 180.00 bucks.Installed new alternator, got jumped off, removed battery cables from boosting it off and 4 minutes later it died as I was letting it charge. Took both batteries to auto zone they said both failed. Bought 2 x 160.00 batteries. Installed them, fired it up and drove home a hour and a half drive. Shut the truck off, started it back up, and was like few, that was an exspensive fix. Got up at 430 am this morning and totally dead truck. Bought a volt meter and tested both batteries after charging them, over 12 amps, Installed battery cables and got 5. 4 amps , mind you there's two batteries connected here. Tried to boost off truck with suv and just get clicking sound with 9.6 volts with both batteries hooked up and the 3rd battery still hooked to suv for boost. Disconnect positive terminals and batteries still read over 12 volts. I would appreciate any help at all here as I'm 500.00 in the hole on this. And can't return to work until I'm riding again. Also voltmeter test gives a high reading when testing between the positive terminal and the positive battery cable. 1.30 volts or something.

 

Try the simple stuff first.

Clean all 4 battery terminals since any corrosion or poor connection could cause this type of problem.

Take a voltage reading on each battery when it is disconnected from the truck. You should see about 12.5 volts if the battery is fully charged.

With both batteries charged and connected, start the truck. If it does not turn over, you have a bad connection or battery cable, probably at the starter.

When the truck is running, wait at least 2 minutes to allow the glow plug relay to drop out and take a voltage reading across both battery terminals. You should see about 13.5 volts if the alternator is charging. It you do not see 13.5 volts, the connector at the alternator is probably bad.

All of this is a starting point so that the real experts here can help you fix the problem.

Lou Braun

 

Did everything you said even installed new connections on positive ends leading to battery. Replaced wire positive between both batteries. Charged both batteries a little over 13 amps each checked alternator it was running at 12.2 amps. Replaced new alternator after testing at autozone and still same reading .

 

Can i just run a new positive from one battery terminal to the alternator to replace wire, or does it have to go through somewhere else first.

 

Did everything you said even installed new connections on positive ends leading to battery. Replaced wire positive between both batteries. Charged both batteries a little over 13 amps each checked alternator it was running at 12.2 amps. Replaced new alternator after testing at autozone and still same reading .

 

Lets see if one of the Mods can get this moved over to the 6.0L Forum.


When dealing with battery cables you can have one that "looks" good
but is still bad under the insulation. That is something to keep in mind
when you find the need to replace an end. The corrosion can wick into the
cabling and create a high resistance spot. This test is called a
Voltage Drop Test.


You will find it very useful for all types of things. It can also show you if you have a
bad ground in the system also.

If you use the link in my signature you can look at info in the 6.0L Tech Folder.
Hope to see you there soon.


Sean <BR>

6.0L Tech Folder

 

moved to the 6.0 forum

 

Clean the grounding locations where they connect to the frame, body, block and starter. Voltage flows from negative to positive, clean them to bare metal.

 

I realize your a little hyper right now but in your writing I think your confusing amps and volts, and honestly with that in not sure what your really telling.

First of all the electrical demands of this motor are so high during the initial 2 minutes of starting that if the batteries are severely depleted you not going to get a good "jump start" situation, especially if the charging output is compromised. So first, the batteries have to be fully charged to get any meaningful data to diagnose.

After charging both batteries, let them sit for 15 minutes and take a voltage reading off each before reconnecting the cables. Connect the cables to the drivers battery, then retake its reading. Connect the passenger battery and take its reading.

Then on restart you can get a voltage reading between a grounding point on the motor and the alternator positive post to read the alternators voltage output. Then you can take a voltage reading between the passengers positive and negative posts. And last, a voltage reading between the drivers battery positive and negative posts.

Just because you bought a rebuilt alternator at the auto parts store means it's good, as there have been bad ones. And the harness connector to the alternator can be bad causing the alternator not to work.

 

Ok batteries fresh everything reads good until i touch the positive probe to the positive terminal and the negative probe to the positive input on the alternator. When testing I found it starts draining the battery significantly. The positive leads from the battery where it splits 4 ways to the gpcm with two harnesses and then to something mounted to the block I think a icm maybe.also a lead down the front of the motor down by the pulleys. How do I find where the short is in between these splits before getting to the alternator? I appreciate all the help as this truck is our money maker and so far I have learned to never trust a autozone employee that doesn't know anything about vehicles and just gives a stab at an answer and making you believe he knows what he's saying. Lol

 

So what your saying is:

Truck not running, key out of the ignition switch.

With all cables connected the batteries read 12.6v+ between the positive and negative terminals on the battery.

Placing the voltmeter probes between a battery positive terminal and the alternator post. You should be reading zero volts between these two points, engine off, key out. Your saying its draining the batteries. Is the voltmeter wire getting hot? What is telling you this connection is draining the batteries, engine off, key out?

 

I'm starting to get confused again, thought I was on the right track, I unplugged the two harnesses and checked the wires coming from the fuse links to the green and black harness it reads the same at 11.96 as does probing the negative and positive sides of battery.i hooked up the green harness of the gpcm check amps at alternator and still read 11.96. I hooked up the black harness and checked amps to the alternator and low and behold it reads 8.6 and starts decending in amps very fast, not to mention it sparks when touching the positive gable that connects these harnesses and alternator wireing to the positive post . Key is out everything is off. What now.

 

Everything still off I touch the positive from positive probe to battery positive and negative to the alternator positive and it starts reading 8.4 and decending the longer it is connected at a fast rate.

 

Do the exact same thing after unplugging the black gpcm harness connector and read 0.00

 

I feel like we're still muddling through, BUT, it sounds like your glow plugs are turning on even though you are not in start mode. These will pull 200 amps down to 80 amps so they can really deplete the batteries if this is so. They should not be on if the key is not in the run position.

To get you to a running condition, as long as we are in warm weather you could keep the black plug off and the truck should still start up, without draining down the batteries. Btw, 11.96 volts is still too low for fully charged batteries.

As far as why the GPM is on when it shouldn't be it could be a fault within the GPM, a fault in the harness, a fault with the PCM, or a fault at the ignition switch. I'm not sure if the '04 wiring is any different then my '03. I need to get to my computer to post the wiring diagram so you can check if there is a turn on voltage to the GMP to determine if it's upstream of an internal GPM fault.

Well, unless I'm going down the wrong path here.